Why do we say that the sun is the driving force for the weather?

The answer for #3 is c but i don't know why

Apump contains 0.5 l of air at 203 kpa. you draw back on the piston of the pump, expanding the volume until the pressure reads 50.8 kpa. what is the new volume of the air pump

8) warming your hands by a fire is an example if which heat transfer? a. conduction b. convection c. radiation d. none of these